We got lucky that Ghost and Provorov were great from the start.
Hopefully Morin's more normal development won't cause too many impatient tears around here. (it will)
Actually Ghost is a good object lesson on player development.
Provorov is a freak of nature, he still makes rookie mistakes, but in general his play is more like a 10 year veteran. Even someone like Kimmo didn't reach this level of play until 23-24 years old.
Ghost is more normal, 23 year old rookie flashed, then struggled the next year, partially due to injury, partially because his defensive game is undeveloped (college, no real AHL experience), partially b/c he's still adjusting to NHL speed in terms of what he can get away with and when he should play it safe.
Morin can improve his skating agility, a better feel for the puck and better judgement of the speed of the game. But jeez, he's only 21 (just 8 months older than Sanheim), he probably won't hit his peak for another 3-4 years. He's so big that it may take him longer just to develop pro level body control.
Sanheim will probably have similar issues that have plagued Ghost in terms of knowing when to use his great offensive skills and when he has to play it safe. A year in the AHL puts him a couple years ahead of Ghost in terms of experience at the same age. He'll also need to fill out to handle NHL strength, but he's 21 and just now finishing growing, so in 2-3 years he'll probably be 6'4 215 lbs and a load to handle.
Myers is the baby at 20, up to 6'5 207, and probably will fill out to 220 lbs or so in the next few years. He probably needs a year in the AHL, but some commentators think he's already NHL ready - but there will be growing pains.
Hagg is the old man at 22, he's listed at 6'2 204, but I'll be he's probably north of 210 lbs at this point. Three years of AHL experience and he's the "worst" of the D-man prospects.
The thing is they're all so physically gifted that by their second season they should be clearly superior to the JAGs we're putting on the ice right now, but may not peak until around the 2020-21 season.